Shareholders' Equity (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Amounts recognized as a component of net periodic pension and other postretirement benefit cost:
Total reclassifications for the period, net of income taxes	$ (0.9)	$ (2.5)
Amortization of Net Loss [Member]
Amounts recognized as a component of net periodic pension and other postretirement benefit cost:
Total before income taxes	(5.9)	(5.1)
Amortization of Prior Service Credit [Member]
Amounts recognized as a component of net periodic pension and other postretirement benefit cost:
Total before income taxes	4.5	1.3
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Amounts recognized as a component of net periodic pension and other postretirement benefit cost:
Total before income taxes	(1.4)	(3.8)
Income tax benefit	$ 0.5	$ 1.3